Estimating the time-course of coherence between single-trial brain signals: an introduction to wavelet coherence

Lachaux, Jean-Philippe; Lutz, Antoine; Rudrauf, David; Cosmelli, Diego; Quyen, Michel Le Van; Martinerie, Jacques; Varela, Francisco J.

doi:10.1016/s0987-7053(02)00301-5

Cited by 313 publications

(258 citation statements)

References 28 publications

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“…Epochs lasting 0.2 s were analyzed. The amplitude and phase of field potential recording do not necessarily change in parallel (Lachaux et al, 2002), so it was necessary to isolate phase synchronization between two sets of field potential data. After Morlet wavelet transform, the phase information over the frequency band was obtained.…”

Section: Methodsmentioning

confidence: 99%

High-Frequency Network Activity, Global Increase in Neuronal Activity, and Synchrony Expansion Precede Epileptic SeizuresIn Vitro

Jiruška¹,

Csicsvari²,

Powell³

et al. 2010

J. Neurosci.

132

151

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How seizures start is a major question in epilepsy research. Preictal EEG changes occur in both human patients and animal models, but their underlying mechanisms and relationship with seizure initiation remain unknown. Here we demonstrate the existence, in the hippocampal CA1 region, of a preictal state characterized by the progressive and global increase in neuronal activity associated with a widespread buildup of low-amplitude high-frequency activity (HFA) (Ͼ100 Hz) and reduction in system complexity. HFA is generated by the firing of neurons, mainly pyramidal cells, at much lower frequencies. Individual cycles of HFA are generated by the near-synchronous (within ϳ5 ms) firing of small numbers of pyramidal cells. The presence of HFA in the low-calcium model implicates nonsynaptic synchronization; the presence of very similar HFA in the high-potassium model shows that it does not depend on an absence of synaptic transmission. Immediately before seizure onset, CA1 is in a state of high sensitivity in which weak depolarizing or synchronizing perturbations can trigger seizures. Transition to seizure is characterized by a rapid expansion and fusion of the neuronal populations responsible for HFA, associated with a progressive slowing of HFA, leading to a single, massive, hypersynchronous cluster generating the high-amplitude low-frequency activity of the seizure.

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Section: Methodsmentioning

confidence: 99%

High-Frequency Network Activity, Global Increase in Neuronal Activity, and Synchrony Expansion Precede Epileptic SeizuresIn Vitro

Jiruška¹,

Csicsvari²,

Powell³

et al. 2010

J. Neurosci.

132

151

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“…The high spatial resolution in this study (approximately of 5 mm) excludes the problem of source localisation that exists in scalp EEG recordings (Lachaux et al, 2002;Kahane, 2003, Lachaux et al, 2007). In the present study, iEEG activity was recorded over a wide frequency range (1-160 Hz) from two implanted epileptic patients, while performing a verbal transformation task.…”

Section: Introductionmentioning

confidence: 92%

Parieto-frontal gamma band activity during the perceptual emergence of speech forms

et al. 2008

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The multistable perception of speech refers to the perceptual changes experienced while listening to a speech form cycled in rapid and continuous repetition, the so-called Verbal Transformation Effect. Because distinct interpretations of the same repeated stimulus alternate spontaneously, this effect provides an invaluable tool to examine how speech percepts are formed in the listener's mind. In order to track the temporal dynamics of brain activity specifically linked to perceptual changes, intracerebral EEG activity was recorded from two implanted epileptic patients while performing a verbal transformation task. To this aim, they were asked to carefully listen to a speech sequence played repeatedly and to press a button whenever they perceived a change in the repeated utterance. For both patients, 300-800 ms prior to the reported perceptual transitions, high frequency activity in the gamma band range (> 40 Hz) was observed within the left inferior frontal and supramarginal gyri. An additional auditory decision task was used to rule out the possibility that the increased gamma band activity was due to the patients' motor responses. These results suggest that articulatory-based representations play a key part in the endogenously driven emergence of auditory speech percepts. The findings are interpreted in relation to theories assuming a link between perception and action in the human speech processing system.

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“…It has been used recently in physics to estimate interactions of nonstationary signals [12]. One of most important features of wavelet coherency is that it considers the phase relationships between two signals.…”

Section: B Wavelet Coherencymentioning

confidence: 99%

Pain Level Measurement Using Discrete Wavelet Transform

Vatankhah¹,

Toliyat²

2016

IJET

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Abstract-Experimental pain has extensively been used as a tool for investigating neural mechanisms and the psychological factors involved in pain processing. The detection of existence and/or level of pain is vital when verbal information is not present e.g. for infants, disabled persons, anesthetized patients and animals also. This study shows that there is a firm relation between Electroencephalogram (EEG) and chronic pain levels and EEG can be used as a reliable tool for detecting, measuring and diagnosing pain levels in humans.This paper proposed a use of wavelet coherency in order to estimate the three pain levels and its usage as an index for pain measurement. Besides, wavelet coefficients are studied to show consistencies with EEG dynamic were extracted to provide the feature vector. A Hidden Markov Model (HMM) and a support vector machine (SVM) scheme was used for pain levels classification. This study confirms the hypothesis that brain pattern under the chronic pain mental task is mapped on EEG and the dependency of brain patterns to EEG is possible and detectable.Index Terms-Chronic pain index, electroencephalogram, SVM, HMM.

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Estimating the time-course of coherence between single-trial brain signals: an introduction to wavelet coherence

Cited by 313 publications

References 28 publications

High-Frequency Network Activity, Global Increase in Neuronal Activity, and Synchrony Expansion Precede Epileptic SeizuresIn Vitro

High-Frequency Network Activity, Global Increase in Neuronal Activity, and Synchrony Expansion Precede Epileptic SeizuresIn Vitro

Parieto-frontal gamma band activity during the perceptual emergence of speech forms

Pain Level Measurement Using Discrete Wavelet Transform

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